Printing-plate.



KARL GEISER AND ALBERT SCHATZMANN, OF BERNE, SWITZERLAND.

PRINTING-PLATE.

Specification of Letters Patent.

Patented July 28, 1908.

Applicatioh filed April 18, 1907. Serial No. 368,986.

ill; all whom it may concern:

Be it known that we, KARL GEISER and ALBERT ScnA'rzMANN, citizens of the Con federation of Switzerland, residing at Berne, in the Canton of Berne and Confederation of Switzerland, have invented certain new and useful Improvements in Printing-Plates, of which the following is a-specification, reference being had to the accompanying drawings.

.Our invention relates to improvements in the tone plates used in the printing of books and the like; and the object of our invention.

is to provide a printing plate of superior material to that heretofore used.

The composition of the plate consists of a mixtureof chlorid of magnesium and mag nesite with starch and talc. As compared with the printing plates now in use and made of sawdust and a mixture of chlorid of magnesium and magnesite (this mixture being known as Sorel cement), our new composition affords the advantage that the plates can he made with a perfectly smooth surface that can be readily and, therefore, very neatly worked, in such manner that neither during the working Off/ll). Surface nor later during the use thereof will small pieces of the pre pared surface become loose. The composition is, therefore, peculiarly adapted for'a planographic printing surface; but it in ay be used tor a relief printing surface and for an' intaglio printing surface as well. vln the ordinary preparation of the composition, one takes equal parts of magnesite, starch and talc and stirs them into a solution of magnesium chlorid until the mixture attains a con- .able molds.

sistency of oil color. Any desired degree of hardness may he obtained byvarx ing the proportions of the t he basic ingredients, magnesite, starch and tale. The preparation or manufacture of the composition then is completed hv casting the mixture in suit- As compared with the printing plzii'es herotofore used (for example, a plate having a wooden base upon which is glued a layer of celluloid), our new printing plate is made up of ahon ogeneous body ormass without a base of wood or of metal. A shifting of the topmost layer, the layer which carries the working face, is :Woided; and, further, the loosening of small pieces during the use of the plate is oln'iatcd. Again, one overcomes the difficulties inherent upon the process of pasting or soldering upon the metal or wooden base the layer which is to he prepared.

No claim: 1

1. A composition for printing platesmade up of a mixture of magnesite, starch and talc with a solution of magnesium chlorid.

2. Aprinting plate made up by casting in suitable molds a mixture of magnesite, starch and talc with a solution of magnosium chlorid.

Signed at said Borne in the presence of the two undersigned witnesses this 8th day of April, A. D. 1907.

KARL GEISER,

ALBERT SCHATZMANN.

Witnesses:

Fmnnmcu NAEGELI, bmanmcn hlONING. 

